bundles/backup-client: use a bash function to do backups instead of repeating the same code over and over

bundles/backup-client/files/generate-backup

@@ -17,18 +17,24 @@ then
     exit 1
 fi
 
+do_backup() {
+    rsync -zaAP --numeric-ids --delete --relative \
+        --rsync-path="/usr/bin/rsync --fake-super" \
+        -e "ssh -o IdentityFile=/etc/backup.priv -o StrictHostKeyChecking=accept-new -p ${port}" \
+        "$1" "$ssh_login":backups/
+
+    # Exit code 24 means some files have vanished during rsync.
+    # I don't know why, but this is very common, apparently?
+    exitcode=$?
+    if [[ $exitcode != 0 ]] && [[ $exitcode != 24 ]]
+    then
+        rsync_errors+=" $exitcode"
+    fi
+}
+
 rsync_errors=""
 % for path in sorted(paths):
-rsync -zaAP --numeric-ids --delete --relative \
-    --rsync-path="/usr/bin/rsync --fake-super" \
-    -e "ssh -o IdentityFile=/etc/backup.priv -o StrictHostKeyChecking=accept-new -p ${port}" \
-    "${path}" "$ssh_login":backups/
-
-exitcode=$?
-if [[ $exitcode != 0 ]] && [[ $exitcode != 24 ]]
-then
-    rsync_errors+=" $exitcode"
-fi
+do_backup "${path}"
 % endfor
 
 if [[ -n "$rsync_errors" ]]